Orateur
Description
The H1 Collaboration reports the first measurement of the 1-jettiness event shape observable $\tau_{1}^{b}$ in neutral-current deep-inelastic electron-proton scattering. The analysis is based on data recorded in 2003-2007 by the H1 detector at the HERA collider for ep collisions at $\sqrt{s}=319$ GeV, with integrated luminosity of 351.1 pb$^{-1}$. The observable $\tau_{1}^{b}$ is equivalent to a thrust observable defined in the Breit frame. The triple differential cross section is presented as a function of $\tau_{1}^{b}$, event virtuality $Q^2$, and inelasticity y, in the kinematic region $Q^2 > 150$ GeV$^2$. The data are compared to predictions from Monte Carlo event generators and NNLO pQCD calculations. These comparisons reveal sensitivity of this observable to QCD parton shower and resummation effects, the magnitude of the strong coupling constant, and proton parton distribution functions, as well as the modeling of hadronization and fragmentation.
